1. Field of the Invention
The present invention generally relates to a scanning system and more particularly relates to a mobile scanner capable of scanning both transparent and opaque materials that itself does not have a separate processor and is not energized by a separate power supply, wherein the power required to support the operation of the mobile scanner is derived from a universal serial bus (USB) connection with a computing device.
2. Description of the Related Art
There are many applications that need optical scanners to convert paper-based objects, such as texts and graphics, to an electronic format that can be subsequently analyzed, distributed and archived. One of the most popular optical scanners is flatbed scanners that convert scanning objects, including pictures and papers, to images that can be used, for example, for building World Wide Web pages and optical character recognition. Another popular optical scanner is what is called sheet-fed scanners that are small and unobtrusive enough to sit between a keyboard and a computer monitor or integrated into a keyboard to provide a handy scanning means. Most optical scanners are referred to as image scanners as the output thereof is generally in digital image format.
With the increasing popularity of notebook computers, there is an emerging need for portable scanners suitable for use as notebook computer accessories. Battery powered handheld scanners have been used to fill this role. To be compact and energy efficient, many of these handheld scanners are manually operated, namely a user would have to hold a handheld scanner over a document to be scanned and move it from one end to another end so as to scan in the entire scanning document. However, the quality of images is not always satisfactory, typically suffering from jittered motions of the manual operations.
With the emergence of sheet-fed scanners, such as those Paper Port series from Visioneer Inc., the sheet-fed scanners gradually replace handheld scanners. Because a sheet-fed scanner operates automatically, namely a scanning document is well controlled to pass through an image sensor in the sheet-fed scanner; the resultant images are generally satisfactory.
The current sheet-fed scanners in the market are standalone devices whereas they generally operate with a computer. In addition to an image sensor, an illumination source and a motion mechanism, a typical sheet-fed scanner has a micro-processor, memory, post-processing circuitry and interface circuitry. Further to energize all the parts in the scanner, there is an external power adapter converting a high AC voltage to a low DC voltage. With all the parts together, a sheet-fed scanner is indeed a self-contained system having an interface to a computing system.
Generally there is a micro-processor in the sheet-fed scanners that controls and operates all the parts to work in synchronization. To reduce the cost of a scanner, the micro-processor in use is typically an 8-bit microprocessor, for example, 8088 from Intel, which is considered nowadays a primitive processor in light of available 32-bit or even 64-bit microprocessors. The overall system performance is thus severely limited by the performance of an 8-bit microprocessor.
There exists a need for a scanner that is compact, energy efficient and lightweight enough to be truly compatible with laptop computers. Additionally, there is a need for mobile scanners that are capable of scanning not only regular papers but also transparent materials (i.e., negative or positive films, transparencies for an overhead projectors or X-ray films). The demand for mobile scanners with the dual-scanning capability is ever increasing in both consumer and business markets.
Accordingly, it is therefore an object of the present invention to provide a portable dual-mode scanner device capable of being powered through a universal serial bus connection where the individual components of the portable scanner are selectively and controllably powered so as to function within the power limitations of a universal serial bus connection port (i.e., 5 Volts, 2.2 watts) without appreciable degradation of a captured image whether that image resides on a transparent media (i.e., a negative) or an opaque media (i.e., paper).
According to one aspect of the present invention, the scanner itself comprises an image sensing module, a motion mechanism and an interface engine. As an important feature in the present invention, the scanner is not powered by an external power adapter rather it is powered through a universal serial connection to a host computer. The image sensing module, including a one-dimensional image sensor, an optical system, a first illumination source (for opaque scanning) and optionally a second illumination source (for transparent scanning), is responsible for imaging content containing media such as a document. The motion mechanism is responsible for moving the document through the image sensing module at a steady speed. Both of the image sensing module and the motion mechanism are coupled to the interface engine that comprises a control circuit. In operation, the circuit receives system control signals from the computing device through the universal serial connection. It then generates logical control signals for the image sensing module and the motion mechanism to operate in synchronization. Further the interface engine draws a power supply from the computing device through a universal serial bus to selectively and controllably energize the image sensing module and the motion mechanism to operate.
According to another aspect of the present invention, the disclosed scanner comprises two demountable cases. The main case houses the image sensing module and the motion mechanism and the base case houses the second illumination source. The first illumination source in the image sensing module provides front illumination to an opaque scanning object while the second illumination source provides back illumination to a transparent scanning object, as such the disclosed scanner is capable of scanning both opaque and transparent materials, a dual scanning feature that has been long sought in the scanning market.
Accordingly, one of the objects in the present invention is to provide a mobile scanner that is of high performance and low cost and so lightweight that it can be used in any conditions.
Other objects, together with the foregoing are attained in the exercise of the invention in the following description and resulting in the embodiment illustrated in the accompanying drawings.